this switch on the s4 activates the afterrun capability. the s4 has a separate control module for the afterrun system and fans. the modeule is under the driver's side frame rail by the bumper shock.

on the A4 there is a simple resistor at this location that controls the fan speed.

this mod is an S4-only mod.

[Modified A4]
2000 Audi A4 1.8tqmsx, K04'd
email:tfcwr at hotmail dot com

(click above pic for dyno video)
6.13 sec CAPS 60F 05/07/07
6.27 sec CAPS: 195 WHP , 186WT @AWE, 60F 10/07/06
6.40 sec CAPS: 220 WHP , 230WT @EPL, 64F 5/13/06
(stock exhaust, stock airbox, stock SMIC)

How does the performance of your A4 stack up? Get a CAPS time!
mod summary:
Performance: K04-15 turbocharger, GIAC K05 programming, APR Exhaust, 3.5bar FPR, 710N BPV, N249 bypassed, Audi TT180 injectors
Efficiency: ExtrudeHoned and gasket matched exhaust manifold, MAF screen delete, APR TIP, APR TBP, snow screen delete, upgraded passat vacuum lines, evoshield intake manifold spacer
Cooling: S4 oil cooler, a/c fan override, S4 vented wheel well liners(both sides), thermal wrapped coolant cross pipe
Venting: ATC valve cover, AWM PCV piping, TT225 pancake valve, second cam oil spash guard
Bracing: S4/V6 engine mounts, APR snub mount, urethane filled RS4/stock transmission mounts
Delivery: AWE stage 2 clutch
Braking: A8/TT font kit w slotted rotors, A6/B6A4 rear kit, Axxis Ultimate pads
Handling: S4/A6 front strut tower bar
Misc: heavy duty belly pan, alternate fog mod, boost gauge with firewall grommet, dentless trunk mod